The autoimmune thyroid diseases and familial thyroid cancers are the current target of molecular thyroid genetics. Unlike the situation in monogenic thyroid diseases, for which the molecular genetics has largely been clarified over the past 20 years, a methodological approach to these more complex forms of thyroid disease has not yet been well established. The determination of susceptibility genes, for example, remains a major challenge. The contributors to this volume are attempting to meet that challenge in research on molecular genetics. Meeting at the first International Symposium on the Genetics of Complex Thyroid Diseases, held in Kyoto, Japan, 20 distinguished researchers from five countries in addition to Japan shared their latest results and engaged in intense discussion, focusing on the autoimmune thyroid diseases and familial thyroid cancers. Their papers collected here are a valuable contribution to the field of the genetics of complex thyroid diseases.

The rapid developments in molecular genetics have clarified many of the muta tions in monogenic thyroid diseases over the last two decades; now the target of molecular thyroid genetics has become the oligogenic thyroid diseases. These include the autoimmune thyroid diseases and familial thyroid cancers, both of which are much commoner than the monogenic diseases. However, the method ological approach to the genetics of these more complex diseases is still far from being well established. Although the discovery of susceptibility genes has been partially accomplished in complex diseases such as asthma, Crohn's dis ease, and types I and II diabetes mellitus, the elucidation of susceptibility genes in complex diseases remains a major challenge. This volume contains papers presented at the International Symposium on the Genetics of Complex Thyroid Diseases. This meeting was held in association with the International Thyroid Congress in Kyoto in October 2000 and sup ported in part by the Japan Intractable Diseases Research Foundation and Knoll Pharmaceuticals Inc. The symposium was the first international symposium con cerning the genetics of complex thyroid diseases and was restricted to the study of the autoimmune thyroid diseases and familial thyroid cancer. Twenty distin guished researchers from the United States, the United Kingdom, France, Ger many, Italy, and Japan were invited. Each presentation precipitated intense dis cussion and there was much consensus during the meeting. Nevertheless, this volume will leave the reader with a clear understanding of how little we still know.